Effects of microwave irradiation on ruminal degradation and in vitro digestibility of soya-bean meal

Using advanced vibrational molecular spectroscopy to detect moist heating induced protein structure changes in cool-climate adapted barley grain

Different techniques have been applied in feed processing to improve ruminal degradation and nutrient utilization in ruminant. There are limited studies investigating how moist heating process impacts barley protein utilization and internal molecular structures. The objectives of this study were to investigate: 1) how moist heating affects barley protein chemical profiles and Cornell Net Carbohydrate and Protein System (CNCPS) subfractions, in situ rumen degradation parameters, and predicted intestinal protein supply and feed milk value; 2) how moist heating affects protein molecular spectral features; and 3) the relationship between protein molecular structure spectral features and protein chemical profiles and metabolic characteristics. The barley variety CDC cowboy samples collected from the research farm during two consecutive years were used. Half of each sample was kept as raw and the other half underwent moist heating. The advanced molecular spectroscopy (attenuated total reflectance-fourier transform infrared, ATR-FTIR) was used to detect the barley protein molecular structure spectral features. It was found that moist heating decreased the fractions of soluble protein and increased the moderately degradable protein and ingestible protein fractions. This further resulted in the changes of in situ rumen degradation parameters and intestinal protein digestion characteristics. The protein molecular structure spectral features detected by using ATR-FTIR spectroscopy can be used as potential predictors for protein related chemical and metabolic parameters.

Microwave-assisted extraction of cyclotides from Viola ignobilis

Cyclotides are an interesting family of circular plant peptides. Their unique three-dimensional structure, comprising a head-to-tail circular backbone chain and three disulfide bonds, confers them stability against thermal, chemical, and enzymatic degradation. Their unique stability under extreme conditions creates an idea about the possibility of using harsh extraction methods such as microwave-assisted extraction (MAE) without affecting their structures. MAE has been introduced as a potent extraction method for extraction of natural compounds, but it is seldom used for peptide and protein extraction. In this work, microwave irradiation was applied to the extraction of cyclotides. The procedure was performed in various steps using a microwave instrument under different conditions. High-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) results show stability of cyclotide structures on microwave radiation. The influential parameters, including time, temperature, and the ratio of solvents that are affecting the MAE potency, were optimized. Optimal conditions were obtained at 20 min of irradiation time, 1200 W of system power in 60 °C, and methanol/water at the ratio of 90:10 (v/v) as solvent. The comparison of MAE results with maceration extraction shows that there are similarities between cyclotide sequences and extraction yields.

Effect of microwave treatment on lucerne fodder

Preliminary research has suggested that in vitro dry matter disappearance of some poor-quality fodder materials can be improved by microwave treatment. A laboratory-scale experiment that treated 50-g samples of lucerne hay in a 750-W microwave oven for 0, 40 and 80 s revealed that dry matter percentage increased by 1.7% as microwave treatment time increased from 0 to 80 s. The in vitro dry matter disappearance increased by 14.9% as microwave treatment increased from 0 to 80 s; however, there was no significant change in crude protein due to excessive variability in the results. This experiment was followed up with a larger-sample experiment in which 25-kg bags of lucerne fodder were treated for 7.5, 15, 22.5 or 30 min in an experimental 6-kW microwave chamber. Dry matter percentage increased by 7.2% as microwave treatment time increased from 0 to 30 min. Microwave treatment significantly increased dry matter disappearance during the in vitro digestion study; however, there were no significant differences between the various microwave treatment times. The 15-min treatment resulted in the greatest increase in dry matter disappearance (5.9%). The crude protein retained in the digestion residues increased by 19.2% as microwave treatment increased from 0 to 30 min. These laboratory studies were followed up with an animal response study in which 22 12–14-month-old Merino wethers were randomly allocated into either a group receiving a maintenance ration of untreated lucerne or a group receiving the same weight of microwave-treated lucerne. The average weight of the control group fluctuated around their starting weight during the 5-week-long trial, as would be expected from feeding a maintenance ration. By the end of the trial their average weight was 0.4% higher than when they started. However the group being fed the microwave-treated lucerne gained 8.1% of their initial bodyweight by the end of the trial.